The relationship between single measures of systolic blood pressure (SBP) in youth and adult levels is weak. We sought to define trajectories of SBP over childhood to determine ability to predict adult hypertension (HTN). In the International Childhood CV Cohort (i3C) Consortium, we constructed SBP trajectories in 11,482 participants (mean age 8.0 + 2.0 years at time of first measure, 47% male, 25% non-Caucasian) who had at least 3 SBPs in youth between the ages of 4 and <20 years assessed with at least 5 years between measures. To account for differences in normal BP by age, sex and height, trajectories were constructed using SBP percentile as defined by the 2017 Clinical Practice Guideline for BP management in youth. We then assessed HTN status (by survey) at mean age 46.7 years in 5,357 of the participants (mean age at first assessment 8.1 + 1.9 years, at self-assessment of HTN 46.7 + 5.7 years. 41% male, 23% non-Caucasian). SAS Proc Traj was employed to construct models with differing numbers of trajectories where all individual trajectories were significant (whether linear, quadratic or cubic). Model fit for each number of trajectories (up to 9) was assessed and trajectories were examined for clinical relevance. The final model selected included 6 trajectories. The prevalence of adult HTN was lowest in the group with low SBP across childhood and adolescence (Low-Low = 20%) and was highest in the group with persistently high SBP (High-High, 49%, chi square <0.001). At first assessment, participants in the High-High group were slightly older (8.7 vs 7.7 years), heavier (BMI 65.2 vs 45.1%), had higher BP (112/61 vs 90/48 mmHg; 27% vs 86% for SBP) and, higher Tchol, LDL, TG, Insulin, Glucose and lower HDL although means were within normal limits (all p<0.001). We conclude that trajectories of BP across childhood may identify youth at high risk for development of HTN in adulthood.